A drug eruption is a skin reaction to a medicine, most often a measles-like rash that starts 4 to 14 days after a new drug such as an antibiotic or an anticonvulsant. Most are mild, but a few become life-threatening reactions such as Stevens-Johnson syndrome or DRESS.
Key symptoms
- Widespread itchy rash days to weeks after starting a new drug
- Pink to red spots and bumps that start on the trunk and spread
- Hives within minutes to hours in immediate allergic reactions
- Fever, painful skin or mouth sores in severe reactions
What you find on exam
- Symmetric red macules and papules that may join together (morbilliform rash)
- Check the mucous membranes: mouth, eyes and genitals
- Look for blisters, skin peeling, and dusky or target-like spots
- Facial swelling, fever and swollen lymph nodes suggest DRESS
Tests
- Detailed medication timeline, including over-the-counter drugs and supplements
- Blood count with eosinophils, and liver and kidney function if there are systemic signs
- Skin biopsy if there are blisters or peeling, or the diagnosis is unclear
Treatment basics
- Stop the suspected drug and switch to an unrelated one
- Topical corticosteroids and oral antihistamines for itch
- Severe reactions: admit, often to a burn or intensive care unit, for supportive care
- Record the allergy in the chart and teach the patient to avoid the drug
Red flags
- Mouth or eye sores, blisters or skin peeling (Stevens-Johnson syndrome or toxic epidermal necrolysis)
- Fever, facial swelling, swollen lymph nodes and abnormal liver tests (DRESS)
- Throat swelling, wheeze or low blood pressure (anaphylaxis)
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.